<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      div {
        width: 500px;
        height: 500px;
        background-color: blue;
        margin: 100px auto;
        /* transition: box-shadow 0.5s; */
        transition: all 1s;
      }
      div:hover {
        box-shadow: 0px 0px 5px 5px rgba(0, 0, 0, 0.3);
        background-color: skyblue;
      }
    </style>
  </head>
  <body>
    <div></div>
  </body>
</html>
